NEW YORK (AP) — A recent time slot switch hasn’t paid dividends for Fox’s lurching “American Idol,” which reached a smaller audience last week than for all but one episode of its rookie season in the summer of 2002.

Thursday’s edition of “Idol” reached 8.4 million viewers, the Nielsen company said. Once television’s most dominant show, last week’s results program barely made it into Nielsen’s top 20 for the week. Wednesday’s show had 9.8 million viewers.

“For a show on that long, there’s going to be viewer fatigue,” said Brad Adgate, an analyst for Horizon Media.

Fox a few weeks ago moved Thursday’s “Idol” to 9 p.m. ET, although the switch hasn’t seemed to affect ratings. Only the July 3, 2002 “Idol” had a smaller audience than last Thursday. Among the 18-to-49-year-old demographic Fox seeks, that was the smallest audience ever.

Fox notes that viewership decline is to be expected for a show on for so long and that, except for one year, the audience has been slipping gradually since 2006. Most longtime programs follow the same trajectory and, even with the slip, “Idol” is still Fox’s most popular show.

With “The X-Factor” now off the air, Fox might consider bringing the show back to its roots with judges Simon Cowell and Paula Abdul, Adgate said.

A likely scenario is a reduction in “American Idol” hours on the air. ABC’s “Dancing With the Stars,” facing a similar decline, condensed the show’s twice-a-week schedule to one, and its new season premiere had 15.4 million viewers last week. “Dancing” was the second most-popular show on the air last week, behind only CBS’ “NCIS.”

CBS won the week in prime time, averaging 8 million viewers. ABC had 6.4 million viewers, NBC had 6.3 million, Fox had 4.3 million, Univision had 2.6 million, the CW had 1.7 million, ION Television had 1.18 million and Telemundo had 1.15 million.

With the help of the NCAA men’s basketball tournament, TBS was the week’s most popular cable network, averaging 2.52 million in prime time, followed by TNT’s 2.47 million. USA had 1.96 million, History had 1.88 million and the Disney Channel had 1.73 million.

NBC’s “Nightly News” topped the evening newscasts with an average of 9.3 million viewers. ABC’s “World News” was second with 8.3 million and the “CBS Evening News” had 7.1 million viewers.